Viscosity control apparatus



Feb. 26, 1952 G, LANTZ 2,587,174

VISCOSITY CONTROL APPARATUS Filed June 3, 1949 2 Si-EFJTSSHEET l lNYfA/TOB DONALD G. LANTZ BY fl l r 036v fi/S nrronnns Feb. 26, 1952 D. G. LANTZ 2,587,174

VISCOSITY CONTROL APPARATUS FiledJune 5, 1949 2 sHEETs -sHEET 2 mvmron DONALD e. LANTZ aga g mmzza Patented Feb. 26, 1952 VISCOSITY CONTROL APPARATUS Donald G. Lantz, Anderson, Ind.,assignr to General Motors-Corporation, Detroit, Mich., a corporation of Delaware Application June 3, 1949, Serial No. 96,979

'7 Claims.

1 This invention relates to the control of viscosity of liquid material, for example, gel lacquer into which articles are dipped to receive a coating which, on cooling, sets to ;a firm,ynon-fiowable gel. The ingredients .of thegel lacquer are mixed with a heated solventin order to obtain the required viscosity-atthe temperature of the bath required for dipcoating. Since thickness of the gel coatingisdependenton the viscosityof the gel lacquer, the control 10f viscosity is necessary to obtain therequired thickness.o'f gel coat. ..As the solvent escapes :by evaporation, it is necessary to iaddzsolvent to prevent too ,high viscosity.

The object of :thepresent .inventionis to provide for adding solvent when viscosity of a liquid. such as described, tends ;to become too great. In the disclosed-:embodimentofthe invention, this is accomplished through the medium of .selsyn units, onebeinga transmitter which senses viscosityof the liquid 'being'tested and the other a receiver which, in obedience-to the transmitter, causes opening of a'valve to admit solvent to the liquid when required to prevent too high viscosity.

Further objects .and advantages of .the present invention will be apparent from the following description, reference being bad to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

(In the drawings:

Fig. 1 isa diagram ofthe.viscositycontrolapparatus.

.Fig. is ajdetaildiagram oraphotoelectric relayincludedinFig. 1.

Fig.3 is a detail-diagram o'fla percentage timer included in Fig.1.

.Figs. 4:and'j15 aresectional views taken, respectively, on lines 4-4 and 5 of Fig. 1.

Fig.6 .is a diagram of .aa viscosityrecorder included in Fig.1.

Referringto Fig. l, tank Ii! contains a liquid indicatedbyupper level. line .I I and supports the fixed frame .base I2 .of a selsyn transmitter unit ST. ..diagrammaticallyrepresented, the unit ST comprises .the frame I2 and supporting rotatable, connectedrparts, namely a nommagnetizable .cup I3, a slotted .magnetizable slotted core I4, a non-conducting drum I5 and ;a cup i5a. Theslottedcore I4 receives .Y-connected windings -2I, 22, 23.connected, respectively, with insulatedslip rings .2Ir, .221, 23? (carried by drum I5) connected by brushes 2 lb, 22b, 23b with wires I, 2, 3, respectively. The core I4 supports arotatableshaft Iii attached to a disc I] submerged in .the liquid to be tested. Shaft I6, journaled insbearingsl 8 provided by. core I4, carriesa shuttie type core I9 surrounded by a winding 20, the ends of which are attached to rings 2 51' and connected by brushes 24b and 25b with wires 24 and 25, respectively. The cap I5a is connected with a shaft 26 supported by frame I2 and connected by gears 21 and 28 with an electric motor 29 which rotates the drum I5, core I4 and windings 2 L22, 23. Rotary motion is imparted to the disc Il through a pin 30, a spiral spring 3| attached to the pin 30 and to a-sleeve 32 whicha set screw 33 .(Fig. 5) secures to shaft I6 in the desired positionof adjustment. The core I9 will lag behind the core I4 to an extent dependent upon the viscosity of the liquid in which the disc I] rotates and upon the adjustment of the torsion of the spring 3|. .In this way, ,the selsyn transmitter senses viscosity. Its windingsZIi, 2|, 22,23 are connected by wires I, 2, 3, 24 and 25 with similar windings 4,d43 of a selsyn receiver SRI .which is constructed somewhat like the transmitter except that the windings 4|, 42, 43 are relatively fixed. Windings 20 and 49 are connected with a source of alternating current connected by a switch SI with wires LI and L2. Wire L2 is connected with wire 25, and wire LI with wire 24 through aresistance RI. The cores carrying them tend to remain in a definite angular position relative to the cores carrying the Y-connected windings. If core I9 is displaced relative to core I4, the core 44 carrying winding will be displaced angularly an amount equal to the angular displacement of core I9. .The winding 40 surrounds a core 34 which is rotatably supported and operates a pointer 45 having a marker which records viscosity on a chart strip 46 (Fig. 6) which is moved by clock work. This strip bears --arcuate time-lines 41 and parallel straight lines 48 indicating viscosity in units known as poises.

In case the viscosity of the liquid should be about 30 poises, for example, the chart strip might be one providing for a record in the range of 22.5 to'37.5 poises. Whendisc I! rotates in a standard liquid having 22.5 poises of viscosity, the core which'supports the windings 4|, 42, 43 is adjustedabout its axis so that'the pointer 45 indicates 22.5 poises on the chart; and, when disc i1 rotates in a standard liquid having 37.5 poises of viscosity, the position of core I9 relative to core I4 is, due to proper adjustment of the torsion of spring 3|, such that the pointer 45 is caused to indicate 37.5 poises on the chart. Therefore, when the liquid to be testedhas 30 poises of viscosity, for example, the pointer will indicate 30poises.

SR2 is a selsyn receiver similar to SRI and has Y-connected coils 5I, 52, 53 connected with wires I, 2, and a coil 59 connected with Wires 24, and wound on a rotatable core 54 connected with a flag 55. Wires LI and L2 are connected also with a lamp 4, rays from which are focused by a lens 4a upon a photo-electric cell 69. While the viscosity of the liquid, being tested, is no greater than the maximum allowable viscosity, the flag 55 blocks the light of lamp 4 from the cell 99. Flag 55 can be adjusted relative to core 54 to unblock the light at a predetermined viscosity.

Cell 69 is part of a photo-electric relay unit shown in detail in Fig. 2. This unit comprises a transformer T having parallel primary coils 62 connected with Wires LI and L2, and secondary coils 63, 64, 65 and a tube 19 having plate 66, grid 61, cathode 69 and heater 69. Plate 66 is connected with coil 'II of relay 89 connected with secondary 64 connected with cathode 6B and with wiper I2 of rheostat 13 connected with secondary 63 which is connected with resistance I4 and condenser I5 connected with the elements of cell 59. Condenser I5 is connected through resistance 76 and grid Bl. Heater 69 is connected with secondary 65. Condenser I1 is in parallel with relay coil II which surrounds a core 8I of relay 89 and which, when energized, effects attraction of an armature 82 to effect closing of contacts 83, 84 normally separated by a spring blade 85. It is understood that, in this relay circuit, a function of the condenser 15 and connected resistances is to split the phase of the grid-circuit A. C. with respect to the plate circuit A. C, Current in the plate circuit is controlled by action of the cell 69 in altering both amplitude and phase of the grid voltage with respect to the plate voltage as the light falling on the cell 69 changes in intensity. When the viscosity of the liquid exceeds a certain value, the flag 55 turns to a position unblocking the beam focused toward the cell 69, thereby causing the tube I9 to pass current sufficient for such energization of coil II that contacts 83, 84 are closed and remain closed until sufficient thinner is added to the liquid to cause its viscosity to decrease to a value such that the flag 55 again blocks the beam focused toward the cell 69.

Contact 83 is connected by wire 9| with a contact 92 of a relay 99 engaged by a contact 93 when coil 94 of relay 99 is energized. A bimetal blade 95 connected with Wire L2 is located in heat receiving relation to the liquid. The liquid temperature is controlled automatically by a device, not shown, which controls application of heat to the liquid. While the temperature of the liquid is correct, blade 95 engages a contact 96, thus connecting coil 94 with wires LI and L2 and contacts 92, 93 remain closed and a green lamp 91 burns to indicate correct temperature. Lowering of temperature cause blade 95 to separate from contact 95 and to engage a contact 98 to cause relay coil 94 and lamp 9'! to be open-circuited and red lamp 99 to burn to indicate too low temperature. A motor I99 connected with Wires LI and L2 operates a temperature-time recorder. When coil 94 is deenergized, contact 93 separates from contact 92 due to biasing action of blade 93a which supports contact 93. Therefore the apparatus is inoperative to cause thinner to be added although necessary. Furthermore, the motor 29 stops since its control relay coil I9I is under control by contacts I92, I93 of relay 99 which open when coil 94 is deenergized. Wires I94, I95 connected with a suitable current source become connected with motor 29 while coil I9I is energized through the following circuit: wir LI, relay contacts I93, I92, coil I9I, wire L2. Armature I98 moves left to cause contacts I96, I91 to connect motor 29 with current source wires I94, I95. The motor, 29 stops when contacts I9, 2, I93 separate since coil I9! is deenergized and a spring I99 returns ccntacts I96, I91 to open position.

Contact 93 is connected by wire III with coil II2 of a solenoid operated valve which controls flow of thinner solvent into the liquid Whose viscosity is .to be controlled. A solenoid armature I I3 is connected with a valve I I4 normally biased against its seat by a spring II5. When coil H2 is energized the valve opens and when the coil is deenergized the valve closes.

The circuit of valve solenoid coil H2 is under control by relay 99 whose contacts are closed while the temperature of the liquid is at least at a certain value, by the relay 89 whose contacts are closed when viscosity of the liquid is above the maximum limit and also by a percentage timer I39 which comprises an electric motor I3I connected with speed-reducing gears such as I32, I33, i3 4, I35 with a cam I36 of spiral contour and engageable with a follower I37 connected with a lade spring I38 carrying a contact I39 connected with wire LI and engageable with a contact I49 carried by a blade spring I4I connected by a wire I42 with contact '94 of relay69. Blades I38 and I4I are attached to a non-conducting block I43 pivoted on a pin I44 attached to a slide I45 and urged. by a spring I46 against a pin I attached to the slide. Slide I45 is guided by a plate I49 and has a follower I49 which is engageable with a cam I59 shaped like cam I36 and rotatable manually. A spring I5I urges the slide I45 right in Figs. 1 and 3 so that the follower I49 engages cam I59. By turning the cam I59, the distance between follower I31 and the center of cam I36 is adjusted so that the proportion of the total time of one revolution of cam I36 during which it operates to maintain engagement of contacts I39 and I 49, can be varied.

The cam I36 of the percentage timer rotates at a constant speed, for example, 2 R. P. H.; and the setting of cam I59 determines the percentage of the thirty minute time of one revolution of cam I59 during which the contacts I39 and I49 are closed; and therefore determines how long the valve I I4 remains open in the event that relay contacts 83, 84 of relay 89 are closed in response to the demand for addition of thinner to the liquid. Therefore duringevery thirty minute period, for example, a certain amount of thinner, determined bythe setting of cam. I59 is added to the liquid. For example, thinner may be added during 10 minutes of the 30 minute period. The remaining 29 minutes of the period is waiting time during which the thinner is mixed with the liquid by a mechanical stirrer. If the amount of thinner added during the one-third part of the 39 minute period is insufficient, the cycle is repeated. By administering the thinner in small doses followed by waiting periods, overdosing of thinner is avoided.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted.

, What is claimed is as follows:

1. Apparatus for controlling viscosity of a liquid comprising a selsyn transmitter havinga stator which is supported for rotation and a rotor, means for rotating the stator at a constant speed,:a=t'disc attached to theiroitor and immersed in 1 the liquid, a spring resisting displacement of theirotorurelative to the statorraiselsynireceiver having :a fixed stator and :a rotor, circuits flconnecting'zthe istator windings iof-th'e transmitter and :receiver, circuits connecting the rotor -vwindings of the transmitter and receiver and with an A. C. source whereby the receiver rotor is caused to take a position relative to the receiver stator corresponding to the position of the transmitter rotor relative to the transmitter stator, and means rendered operative in response to a predetermined displacement of the receiver rotor relative to the receiver stator for causing admission of thinner to the liquid.

2. Apparatus according to claim 1 further characterized by the provision of a photo-electric relay upon the cell of which a light beam is focused, by the provision of a beam intercepter connected with the receiver rotor and so positioned relative thereto that the intercepter moves to non-blocking position when the rotor of the receiver is displaced relative to its stator a certain angular distance and by the provision of means which is caused to admit thinner to the liquid while the photo-electric relay is energized and which operates to discontinue flow of thinner to the liquid when the photo-electric relay is deenergized.

3. Apparatus according to claim 1 further characterized by the provision of a photo-electric relay upon the cell of which a light beam is focused, by the provision of a beam intercepter connected with the receiver rotor and so positioned relative thereto that the intercepter moves to non-blocking position when the rotor of the receiver is displaced relative to its stator a certain angular distance, contacts associated with said photo-electric relay which are closed when the interceptor is moved to non-blocking position, a valve for controlling admission of thinner to the liquid, an electromagnet for opening the valve, a percentage timer operated by the current source and having a pair of contacts, and a circuit for connecting the current source with the coil of the valve electromagnet and including contacts of the photo-electric relay and contacts of the percentage timer.

4. Apparatus according to claim 1 further characterized by the provision of a photo-electric relay upon the cell of which a light beam is focused, by the provision or a beam intercepter connected with the receiver rotor and so positioned relative thereto that the intercepter moves to non-blocking position when the rotor of the receiver is displaced relative to its stator a. certain angular distance, contacts associated with said photo-electric relay which are closed when the interceptor is moved to non-blocking position, a valve for controlling admission of thinner to the liquid, an electromagnet for opening the valve, a percentage timer operated by the current source and having a pair of contacts, a second relay having a coil and contacts closed by energization of the second relay coil, means for connecting the second relay coil with the current source and including a thermal switch responsive to temperature of the liquid and adapted to close when the temperature of the liquid reaches a predetermined figure and open when the temperature of the liquid drops below said figure, and a circuit for connecting the current source with the coil of the valve electromagnet and including contacts of the photo-electric "iii relay and contacts :of rthe percentage itimer and contacts of the secondrelay.

*5. Apparatus accordingto claim 1 further. characterized by "the hprovisionlof La tphoto-electric'relay upon the cell of which a light beam isfocused, by the provision of i a beam interceptor connected with the receiver rotor and so positioned relative thereto that the intercepter moves to non-blocking position when the rotor of the receiver is displaced relative to its stator a certain-angular-dis tance, contacts associated with said photo-electric relay which are closed when the interceptor is moved to non-blocking position, a valve for controlling admission of thinner to the liquid, an

.; electromagnet for opening the valve, a percentage timer operated by the current source and having a pair of contacts, a second relay having a coil and two pairs of contacts closed by energization of the relay coil, means for connecting the second relay coil with the current source and including a thermal control responsive to temperature of the liquid and adapted to close when the temperature of the liquid reaches a predetermined figure and open when the temperature of the liquid drops below said figure, means under control by one pair of contacts of the second relay for controlling the stator rotating means of the selsyn transmitter, a circuit for connecting the current source with the coil of the valve eleci, trornagnet and including contacts of the photoelectric relay and contacts of the percentage timer and the other pair of contacts of the second relay.

6. A viscosity control device, comprising; two

., interconnected selsyn motors which are in balance with each other so that the rotor and stator of each motor are normally maintained in predetermined angular relation to one another, a disc carried by the rotor of one motor adapted to be immersed in the fluid, the viscosity of which is to be maintained constant, means associated with said rotor and disc for biasing the rotor out of the predetermined angular relation with its stator a quantity equal to the fluid drag on the disc whereby the said drag equalizes the bias of said means when the viscosity of the fluid is at a desired viscosity and wherein the equalization of the bias is destroyed when the viscosity of the fluid varies from the desired viscosity whereupon the rotor of the second motor is thrown out of balance a like amount with respect to its angular relation with its stator, and control means actuated by the out of balance movement only of the second rotor for causing an adjustment of the viscosity of the fluid to again bring the device into balance.

'7. A viscosity control device, comprising in combination; a pair of selsyn motors each having a rotor and a stator normally in balance with respect to one another, said motors being electrically interconnected and adjusted so that they are in balance with one another, a viscosity sensing device immersed in the fluid, the viscosity of which is being controlled for throwing the rotor and stator of the first motor out of balance, compensating means acting on the said rotor for counteracting the effect of said sensing device when the viscosity of the fluid is at a predetermined viscosity whereby the rotor and stator of the first motor are out of balance only when the viscosity of the fluid is not, said predetermined viscosity for simultaneously causing the rotor and stator of the second motor to be thrown out of balance a like amount, and control means actuated by the second rotor only when said rotor 7 is out of balance with its stator for causing a controlled adjustment of the viscosity of the fluid to the predetermined viscoslty, whereby the first motor is again balanced for balancing the second motor.

DONALD G. LANTZ.

REFERENCES CITED UNITED STATES PATENTS Number Name Date French Sept. 5, 1933 Croft June 1, 1943 Hurndall Aug. 29, 1944 Pecker Oct. 26, 1948 Weisz Get. 18, 1949 

